Drag reducing copolymers for cold fluid applications

ABSTRACT

Drag reducing compositions comprising polymer particles, where the polymer particles include copolymers comprising the residues of at least one methacrylate monomer and at least one comonomer having a polymerizable vinyl group, where the comonomer has no more than one pendant substituent per vinyl carbon. The drag reducing compositions can have improved dissolution rates in hydrocarbon-containing fluids. The drag reducing compositions can be added to a hydrocarbon-containing fluid to decrease the pressure drop associated with the turbulent flow of the hydrocarbon-containing fluid through a conduit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to drag reducing compositionscomprising copolymers. More specifically, the present invention relatesto drag reducing compositions having copolymers comprising the residuesof at least one methacrylate monomer and at least one comonomer havingno more than one pendant substituent per vinyl carbon.

2. Description of the Prior Art

When fluids are transported by a pipeline, a drop in fluid pressuretypically occurs due to friction between the wall of the pipeline andthe fluid. Due to this pressure drop, for a given pipeline, fluid mustbe transported with sufficient pressure to achieve a desired throughput.When higher flow rates are desired through the pipeline, more pressuremust be applied due to the fact that as flow rates are increased thedifference in pressure caused by the pressure drop also increases.However, design limitations on pipelines limit the amount of pressurethat can be employed. The problems associated with pressure drop aremost acute when fluids are transported over long distances. Suchpressure drops can result in inefficiencies that increase equipment andoperation costs.

To alleviate the problems associated with pressure drop, many in theindustry utilize drag reducing additives in the flowing fluid. When theflow of fluid in a pipeline is turbulent, high molecular weightpolymeric drag reducers can be employed to enhance the flow. A dragreducer is a composition capable of substantially reducing friction lossassociated with the turbulent flow of fluid through a pipeline. The roleof these additives is to suppress the growth of turbulent eddies, whichresults in higher flow rate at a constant pumping pressure. Ultrahighmolecular weight polymers are known to function well as drag reducers,particularly in hydrocarbon liquids. In general, drag reduction dependsin part upon the molecular weight of the polymer additive and itsability to dissolve in the hydrocarbon under turbulent flow. Effectivedrag reducing polymers typically have molecular weights in excess offive million. However, many conventional drag reducers do not performwell in colder temperature fluids, which may be due to lower dissolutionrates caused by lower temperatures.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, there is provided a dragreducing composition comprising: a continuous phase and a plurality ofdrag reducing polymer particles. At least a portion of the polymerparticles comprise copolymers containing the residues of at least onemethacrylate monomer and the residues of at least one comonomer, and thecomonomer comprises a polymerizable vinyl group having no more than onependant substituent per vinyl carbon.

In another embodiment of the present invention, there is provided amethod of making a drag reducer. The method of this embodimentcomprises: (a) combining water, at least one surfactant, at least onemethacrylate monomer, and at least one comonomer to thereby form areaction mixture; and (b) subjecting the reaction mixture to emulsionpolymerization or suspension polymerization to thereby form a latexcomprising a continuous phase and a plurality of drag reducing copolymerparticles comprising residues of the methacrylate monomer and residuesof the comonomer, where the comonomer comprises a polymerizable vinylgroup having no more than one pendant substituent per vinyl carbon.

In yet another embodiment of the present invention, there is provided amethod for reducing the pressure drop associated with the turbulent flowof a hydrocarbon-containing fluid through a pipeline. The method of thisembodiment comprises: (a) introducing a drag reducing composition intothe hydrocarbon-containing fluid, where the drag reducing composition isin the form of a latex or suspension comprising a continuous phase and aplurality of drag reducing polymer particles comprising copolymerscontaining the residues of at least one methacrylate monomer and theresidues of at least one comonomer, where the comonomer comprises apolymerizable vinyl group having no more than one pendant substituentper vinyl carbon; and (b) flowing the resulting treatedhydrocarbon-containing fluid through said pipeline. Thehydrocarbon-containing fluid of this embodiment has an averagetemperature of 25° C. or less.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A preferred embodiment of the present invention is described in detailbelow with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic illustration of a test apparatus used to performdissolution rate tests on various drag reducers;

FIG. 2 is an isometric view of the stirrer employed in the dissolutionrate tests;

FIG. 3 is a top view of the stirrer employed in the dissolution ratetests; and

FIG. 4 is a side view of the stirrer employed in the dissolution ratetests.

DETAILED DESCRIPTION

In accordance with one embodiment of the present invention, a dragreducing composition (i.e., a drag reducer) is provided comprising aplurality of drag reducing polymer particles comprising copolymerscontaining the residues of at least two different monomers. The dragreducer of the present invention can be employed to at least partiallyreduce the pressure drop associated with the turbulent flow of ahydrocarbon-containing fluid through a conduit (e.g., a pipeline).

In one embodiment of the present invention, the above-mentioned dragreducing composition can comprise polymer particles containingcopolymers formed via emulsion polymerization or suspensionpolymerization of a reaction mixture comprising at least two monomers, acontinuous phase, at least one surfactant, and an initiation system. Asused herein, the terms “emulsion polymer” and “emulsion drag reducingpolymer” shall denote any polymer prepared via emulsion polymerization.As discussed in greater detail below, the resulting reaction product ofthe emulsion polymerization can be in the form of a latex drag reducercomposition. As used herein, the terms “suspension polymer” and“suspension drag reducing polymer” shall denote any polymer prepared viasuspension polymerization. As discussed below, the resulting reactionproduct of the suspension polymerization can be in the form of asuspension drag reducer composition.

The continuous phase of the drag reducer composition can generallycomprise at least one component selected from the group consisting ofwater, one or more alcohols, one or more polyols, and mixtures thereof.When water is the selected constituent of the continuous phase, thereaction mixture can also comprise a buffer. Additionally, as describedin more detail below, the continuous phase can optionally comprise ahydrate inhibitor. As described in more detail below, a stabilizeroptionally can be added.

As mentioned above, the copolymer of the drag reducing compositions ofthe present invention can comprise the residues of at least twodifferent monomers. In one embodiment, at least one of the monomersemployed in producing the drag reducing composition can be amethacrylate monomer. Methacrylate monomers suitable for use in thepresent invention can have the following structure:

In one embodiment, R₁ of the above structure can comprise a C₁ to C₂₀alkyl, isoalkyl, cycloalkyl, aryl, or aryl-substituted alkyl. In anotherembodiment, methacrylate monomers useful in the present invention cancomprise C₄-C₂₀ alkyl, isoalkyl, cycloalkyl, C₆-C₂₀ substituted orunsubstituted aryl, or aryl-substituted C₁-C₁₀ alkyl esters ofmethacrylic acid. In still another embodiment, the methacrylate monomeremployed in the present invention can comprise 2-ethylhexylmethacrylate.

The second monomer (a.k.a., comonomer) employed in making the dragreducing compositions of the present invention can comprise any monomerhaving a polymerizable vinyl group that has no more than one pendantsubstituent per vinyl carbon. As used herein, the term “polymerizablevinyl group” shall denote the carbon/carbon double bond of the monomerwhere polymerization of that monomer occurs. As used herein, the term“pendant substituent” shall denote any non-hydrogen atom or moietycovalently bonded to the vinyl carbon atom.

In one embodiment, the comonomer of the present invention can compriseone or more of the following structures:

where R₂ can be —C(O)OR₃, phenyl or aryl, heterocyclic radical, such as,for example, a pyridinyl or pyridyl, —OR₄, or —O(O)CR₅; where R₃ can bea C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, or aryl-substitutedalkyl; where R₄ can be a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl; where R₅ can be a C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, or aryl-substituted alkyl; and/or

where X can be O, or N—R₆, wherein R₆ is H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, or aryl-substituted alkyl, or ring-opened alkyldiesters; and/or

where R₇ and R₈ can independently be H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or heterocyclic radical.

In another embodiment, comonomers useful in the present invention canhave the following structure:

The R₉ moiety in the above structure can be a straight or branchedaliphatic alkyl group having 8 or fewer carbon atoms, 6 or fewer carbonatoms, or 4 or fewer carbon atoms. Additionally, the comonomer can beselected from the group consisting of n-butyl acrylate; 2-ethylhexylacrylate; 3,5,5-trimethylhexyl acrylate; tert-butyl acrylate;2-phenylethyl acrylate; iso-butyl acrylate; isobornyl acrylate; n-hexylacrylate; sec-butyl acrylate; ethyl acrylate; and lauryl acrylate.Furthermore, in one embodiment the comonomer can comprise n-butylacrylate.

The surfactant used in the above-mentioned reaction mixture can includeat least one high HLB anionic or nonionic surfactant. The term “HLBnumber” refers to the hydrophile-lipophile balance of a surfactant in anemulsion. The HLB number is determined by the methods described by W. C.Griffin in J. Soc. Cosmet. Chem., 1, 311 (1949) and J. Soc. Cosmet.Chem., 5, 249 (1954), which are incorporated herein by reference. Asused herein, the term “high HLB” shall denote an HLB number of 7 ormore. The HLB number of surfactants for use with forming the reactionmixture can be at least about 8, at least about 10, or at least 12.

Exemplary high HLB anionic surfactants include, but are not limited to,high HLB alkyl sulfates, alkyl ether sulfates, dialkyl sulfosuccinates,alkyl phosphates, alkyl aryl sulfonates, and sarcosinates. Suitableexamples of commercially available high HLB anionic surfactants include,but are not limited to, sodium lauryl sulfate (available as RHODAPON®LSB from Rhodia Incorporated, Cranbury, N.J.), dioctyl sodiumsulfosuccinate (available as AEROSOL® OT from Cytec Industries, Inc.,West Paterson, N.J.), 2-ethylhexyl polyphosphate sodium salt (availablefrom Jarchem Industries Inc., Newark, N.J.), sodium dodecylbenzenesulfonate (available as NORFOX 40 from Norman, Fox & Co., Vernon,Calif.), and sodium lauroylsarcosinic (available as HAMPOSYL® L-30 fromHampshire Chemical Corp., Lexington, Mass.).

Exemplary high HLB nonionic surfactants include, but are not limited to,high HLB sorbitan esters, PEG fatty acid esters, ethoxylated glycerineesters, ethoxylated fatty amines, ethoxylated sorbitan esters, blockethylene oxide/propylene oxide surfactants, alcohol/fatty acid esters,ethoxylated alcohols, ethoxylated fatty acids, alkoxylated castor oils,glycerine esters, linear alcohol ethoxylates, and alkyl phenolethoxylates. Suitable examples of commercially available high HLBnonionic surfactants include, but are not limited to, nonylphenoxy andoctylphenoxy poly(ethyleneoxy) ethanols (available as the IGEPAL® CA andCO series, respectively from Rhodia, Cranbury, N.J.), C8 to C18ethoxylated primary alcohols (such as RHODASURF® LA-9 from Rhodia Inc.,Cranbury, N.J.), C11 to C15 secondary-alcohol ethoxylates (available asthe TERGITOL® 15-S series, including 15-S-7,15-S-9,15-S-12, from DowChemical Company, Midland, Mich.), polyoxyethylene sorbitan fatty acidesters (available as the TWEEN® series of surfactants from Uniquema,Wilmington, Del.), polyethylene oxide (25) oleyl ether (available asSIPONIC Y-500-70 from Americal Alcolac Chemical Co., Baltimore, Md.),alkylaryl polyether alcohols (available as the TRITON® X series,including X-100, X-165, X-305, and X-405, from Dow Chemical Company,Midland, Mich.).

In one embodiment, the initiation system for use in the above-mentionedreaction mixture can be any suitable system for generating free radicalsnecessary to facilitate emulsion polymerization or suspensionpolymerization. Possible initiators include, but are not limited to,persulfates (e.g., ammonium persulfate, sodium persulfate, potassiumpersulfate), peroxy persulfates, and peroxides (e.g., tert-butylhydroperoxide) used alone or in combination with one or more reducingcomponents and/or accelerators. Possible reducing components include,but are not limited to, bisulfites, metabisulfites, ascorbic acid,erythorbic acid, and sodium formaldehyde sulfoxylate. Possibleaccelerators include, but are not limited to, any composition containinga transition metal having two oxidation states such as, for example,ferrous sulfate and ferrous ammonium sulfate. Alternatively, knownthermal and radiation initiation techniques can be employed to generatethe free radicals. An example is polymerization initiated using azocompounds such as azobisisobutyronitrile (available from AldrichChemical Co.). In another embodiment, any polymerization andcorresponding initiation or catalytic methods known by those skilled inthe art may be used in the present invention. For example, whenpolymerization is performed by methods such as addition or condensationpolymerization, the polymerization can be initiated or catalyzed bymethods such as cationic, anionic, or coordination methods.

When water is used to form the above-mentioned reaction mixture, thewater can be purified water such as distilled or deionized water.However, the continuous phase of the emulsion can also comprise polarorganic liquids or aqueous solutions of polar organic liquids, such asthose listed below with regards to suitable hydrate inhibitors.

As previously noted, the reaction mixture can optionally include abuffer. The buffer can comprise any known buffer that is compatible withthe initiation system. Examples of buffers suitable for use in thepresent invention include, but are not limited to, carbonate, phosphate,and/or borate buffers.

As previously noted, the reaction mixture can optionally include atleast one hydrate inhibitor. The hydrate inhibitor can be athermodynamic hydrate inhibitor such as, for example, an alcohol and/ora polyol. In one embodiment, the hydrate inhibitor can comprise one ormore polyhydric alcohols and/or one or more ethers of polyhydricalcohols. Suitable polyhydric alcohols include, but are not limited to,monoethylene glycol, diethylene glycol, triethylene glycol,monopropylene glycol, and/or dipropylene glycol. Suitable ethers ofpolyhydric alcohols include, but are not limited to, ethylene glycolmonomethyl ether, diethylene glycol monomethyl ether, propylene glycolmonomethyl ether, and dipropylene glycol monomethyl ether.

Generally, the hydrate inhibitor can be any composition that when mixedwith distilled water at a 1:1 weight ratio produces a hydrate inhibitedliquid mixture having a gas hydrate formation temperature at 2,000 psiathat is lower than the gas hydrate formation temperature of distilledwater at 2,000 psia by an amount in the range of from about 10 to about150° F., in the range of from about 20 to about 80° F., or in the rangeof from 30 to 60° F. For example, monoethylene glycol qualifies as ahydrate inhibitor because the gas hydrate formation temperature ofdistilled water at 2,000 psia is about 70° F., while the gas hydrateformation temperature of a 1:1 mixture of distilled water andmonoethylene glycol at 2,000 psia is about 28° F. Thus, monoethyleneglycol lowers the gas hydrate formation temperature of distilled waterat 2,000 psia by about 42° F. when added to the distilled water at a 1:1weight ratio. It should be noted that the gas hydrate formationtemperature of a particular liquid may vary depending on thecompositional make-up of the natural gas used to determine the gashydrate formation temperature. Therefore, when gas hydrate formationtemperature is used herein to define what constitutes a “hydrateinhibitor,” such gas hydrate temperature is presumed to be determinedusing a natural gas composition containing 92 mole percent methane, 5mole percent ethane, and 3 mole percent propane.

As previously discussed, the reaction mixture optionally can include atleast one stabilizer, also known as a suspending agent. The suspendingagent can be of the form of one or more finely divided inorganic solidsand/or water-soluble polymers; such suspending agents also can be calleda protective colloid. Examples of finely divided inorganic solidsinclude, but are not limited to, talc or fumed silica (both availablefrom Aldrich Chemical Co.). An example of a protective colloid ispoly(vinyl alcohol), 87-89% hydrolyzed (available from Aldrich ChemicalCo.).

In forming the reaction mixture, the at least two monomers, water, theat least one surfactant, and optionally the hydrate inhibitor, can becombined under a substantially oxygen-free atmosphere that is maintainedat less than about 1,000 ppmw oxygen or less than 100 ppmw oxygen. Thesubstantially oxygen-free atmosphere can be maintained by continuouslypurging the reaction vessel with an inert gas such as nitrogen and/orargon. The temperature of the system can be kept at a level in the rangeof from the freezing point of the continuous phase up to about 60° C.,in the range of from about 0 to about 45° C., or in the range of from 0to 30° C. The system pressure can be maintained in the range of fromabout 5 to about 100 psia, in the range of from about 10 to about 25psia, or about atmospheric pressure. However, higher pressures up toabout 300 psia can be useful to polymerize certain monomers, such asdiolefins.

Next, a buffer can be added, if required, followed by addition of theinitiation system, either all at once or over time. The polymerizationreaction is carried out for a sufficient amount of time to achieve atleast about 90 percent conversion by weight of the monomers. Typically,this time period is in the range of from between about 1 to about 10hours, or in the range of from 3 to 5 hours. During polymerization, thereaction mixture can be continuously agitated.

The following table sets forth approximate broad and narrow ranges forthe amounts of the ingredients present in the reaction mixture.

Ingredient Broad Range Narrow Range Total Monomer 10-60% 30-50% (wt. %of reaction mixture) Water 20-80% 50-70% (wt. % of reaction mixture)Surfactant 0.1-10%  0.25-6%   (wt. % of reaction mixture) Initiationsystem Monomer:Initiator 1 × 10³:1-5 × 10⁶:1 5 × 10³:1-2 × 10⁶:1 (molarratio) Monomer:Reducing Comp. 1 × 10³:1-5 × 10⁶:1 1 × 10⁴:1-2 × 10⁶:1(molar ratio) Accelerator:Initiator 0.001:1-10:1 0.005:1-1:1 (molarratio) Buffer 0 to amount necessary to reach pH of initiation (initiatordependent, typically between about 6.5-10) Optional hydrate inhibitor Ifpresent, the hydrate inhibitor can have a hydrate inhibitor-to-waterweight ratio from about 1:10 to about 10:1, about 1:5 to about 5:1, or2:3 to 3:2.

The emulsion polymerization reaction achieved in the above-describedreaction mixture can yield a latex composition comprising a dispersedphase of solid particles and a liquid continuous phase. The latex can bea stable colloidal dispersion comprising a dispersed phase of highmolecular weight polymer particles and a continuous phase comprisingwater. The colloidal particles can make up in the range of from about 10to about 60 percent by weight of the latex, or in the range of from 40to 50 percent by weight of the latex. The continuous phase can comprisewater, the high HLB surfactant, the hydrate inhibitor (if present), andbuffer as needed. Water can be present in the range of from about 20 toabout 80 percent by weight of the latex, or in the range of from about40 to about 60 percent by weight of the latex. The high HLB surfactantcan make up in the range of from about 0.1 to about 10 percent by weightof the latex, or in the range of from 0.25 to 6 percent by weight of thelatex. As noted in the table above, the buffer can be present in anamount necessary to reach the pH required for initiation of thepolymerization reaction and is initiator dependent. Typically, the pHrequired to initiate a reaction is in the range of from 6.5 to 10.

The suspension polymerization reaction achieved in the above-describedreaction mixture can yield a suspended polymer composition comprising adispersed phase of solid particles and a liquid continuous phase. Thesuspension can be a stable colloidal dispersion comprising a dispersedphase of high molecular weight polymer particles and a continuous phasecomprising water. The colloidal particles can make up in the range offrom about 10 to about 60 percent by weight of the suspension, or in therange of from 40 to 50 percent by weight of the suspension. Thecontinuous phase can comprise water, the high HLB surfactant, thehydrate inhibitor (if present), and buffer as needed. Water can bepresent in the range of from about 20 to about 80 percent by weight ofthe suspension, or in the range of from about 40 to about 60 percent byweight of the suspension. The high HLB surfactant can make up in therange of from about 0.1 to about 10 percent by weight of the suspension,or in the range of from 0.25 to 6 percent by weight of the suspension.As noted in the table above, the buffer can be present in an amountnecessary to reach the pH required for initiation of the polymerizationreaction and is initiator dependent. Typically, the pH required toinitiate a reaction is in the range of from 6.5 to 10.

When a hydrate inhibitor is employed in the reaction mixture, it can bepresent in the resulting latex or suspension in an amount that yields ahydrate inhibitor-to-water weight ratio in the range of from about 1:10to about 10:1, in the range of from about 1:5 to about 5:1, or in therange of from 2:3 to 3:2. Alternatively, all or part of the hydrateinhibitor can be added to the latex or suspension after polymerizationto provide the desired amount of hydrate inhibitor in the continuousphase of the latex or suspension.

As mentioned above, at least two monomers can be employed when preparingthe drag reducing composition of the present invention, thus resultingin a drag reducer comprising a plurality of polymer particles comprisingcopolymers. In one embodiment, the resulting copolymers can compriseresidues of the above-mentioned methacrylate monomer in an amount in therange of from about 10 to about 99 weight percent, in the range of fromabout 20 to about 97 weight percent, or in the range of from 40 to 95weight percent, based on the total weight of the copolymer.Additionally, the copolymers can comprise residues of theabove-described comonomer in an amount in the range of from about 1 toabout 90 weight percent, in the range of from about 3 to about 80 weightpercent, or in the range of from 5 to 60 weight percent, based on thetotal weight of the copolymer.

In one embodiment, the copolymers of the resulting drag reducingcomposition can comprise at least partially saturated hydrocarbonbackbones comprising a plurality of saturated carbon atoms. Thehydrocarbon backbones of the copolymers can be at least 90 percentsaturated, at least 95 percent saturated, at least 99 percent saturated,or substantially fully saturated. In one embodiment of the presentinvention, fewer than 50 percent, fewer than 45 percent, or fewer than40 percent of the saturated carbon atoms in the hydrocarbon backbone ofthe copolymer have more than one pendant substituent.

Though not wishing to be bound by theory, the inventors haveunexpectedly discovered that employing a methacrylate monomer with acomonomer comprising a polymerizable vinyl group having no more than onependant substituent per vinyl carbon appears to produce a copolymerhaving improved rates of dissolution in hydrocarbon-containing fluids atlower temperatures. Similarly, copolymers having fewer saturatedbackbone carbon atoms comprising more than one pendant substituent seemto exhibit improved rates of dissolution in hydrocarbon-containingfluids at lower temperatures. Thus, in one embodiment of the presentinvention, the polymer particles of the drag reducing composition canhave a hydrocarbon dissolution rate constant of at least 0.01 min⁻¹, atleast 0.05 min⁻¹, or at least 0.1 min⁻¹ in a mixture of kerosene andisopropyl alcohol (“IPA”) in a volume ratio of 95:5 kerosene:IPA.Hydrocarbon dissolution rate constants are determined in accordance withthe procedure outlined below in the “Dissolution Rate Testing” portionof the Examples section.

In one embodiment of the present invention, the emulsion drag reducingpolymer of the dispersed phase of the latex can have a weight averagemolecular weight (M_(w)) of at least about 1×10⁶ g/mol, at least about2×10⁶ g/mol, or at least 5×10⁶ g/mol. The colloidal particles of theemulsion drag reducing polymer can have a mean particle size of lessthan about 10 micrometers, less than about 1,000 nm (1 micrometer), inthe range of from about 10 to about 500 nm, or in the range of from 50to 250 nm. At least about 95 percent by weight of the colloidalparticles can be larger than about 10 nm and smaller than about 500 nm.At least about 95 percent by weight of the particles can be larger thanabout 25 nm and smaller than about 250 nm. The continuous phase can havea pH in the range of from about 4 to about 10, or in the range of fromabout 6 to about 8, and contains few if any multi-valent cations.

In one embodiment of the present invention, the suspended drag reducingpolymer of the dispersed phase of the suspension drag reducing polymercan have a weight average molecular weight (M_(w)) of at least about1×10⁶ g/mol, at least about 2×10⁶ g/mol, or at least 5×10⁶ g/mol. Thecolloidal particles of the suspended drag reducing polymer can have amean particle size of less than about 1000 micrometers, less than about500 micrometers, in the range of from about 1 to about 500 micrometers,or in the range of from 10 to 400 micrometers. At least about 95 percentby weight of the colloidal particles can be larger than about 1micrometer and smaller than about 500 micrometers. At least about 95percent by weight of the particles can be larger than about 10micrometers and smaller than about 400 micrometers. The continuous phasecan have a pH in the range of from about 4 to about 10, or in the rangeof from about 6 to about 8, and contains few if any multi-valentcations.

In one embodiment of the present invention, the above-described dragreducing composition can be added to a hydrocarbon-containing fluid. Theresulting treated hydrocarbon-containing fluid can then be transportedthrough a pipeline. The hydrocarbon-containing fluid can comprise aliquid phase hydrocarbon, a non-liquid phase hydrocarbon, and/or anon-hydrocarbon fluid. In one embodiment, the hydrocarbon-containingfluid can comprise at least about 50 weight percent of a liquid phasehydrocarbon. Additionally, the hydrocarbon-containing fluid can comprisecrude oil. Furthermore, the hydrocarbon-containing fluid of the presentinvention can have an average temperature of 25° C. or less, 22° C. orless, or 20° C. or less.

The resulting treated hydrocarbon-containing fluid can comprise acumulative amount of the drag reducing copolymers sufficient to achievea reduction in drag associated with the turbulent flow of thehydrocarbon-containing fluid through the pipeline. In one embodiment,the treated hydrocarbon-containing fluid can have a cumulativeconcentration of drag reducing copolymers in the range of from about 0.1to about 500 ppmw, in the range of from about 0.5 to about 200 ppmw, inthe range of from about 1 to about 100 ppmw, or in the range of from 2to 50 ppmw. Typically, at least 50 weight percent, at least 75 weightpercent, or at least 95 weight percent of the drag reducing copolymerparticles can be dissolved by the hydrocarbon-containing fluid.Additionally, the drag reducers employed in the present invention canprovide significant percent drag reduction during transport of thehydrocarbon-containing fluid through a pipeline. For example, the dragreducers can provide at least about 5 percent drag reduction or at least10 percent drag reduction.

The following examples are intended to be illustrative of the presentinvention in order to teach one of ordinary skill in the art to make anduse the invention and are not intended to limit the scope of theinvention in any way.

EXAMPLES Drag Reducer Preparation Procedure

Each of the polymer samples employed in the following examples wereprepared according to the following method. Polymerization was performedin a 300 mL jacketed reaction kettle fitted with a condenser, mechanicalstirrer, thermocouple, septum ports, and nitrogen inlets/outlets. Thekettle was charged with 0.230 g of sodium hydrogen phosphate, 0.230 gpotassium dihydrogen phosphate, 4.47 g sodium dodecyl sulfate and purgedwith nitrogen for at least one hour. The kettle was then charged with120 mL of deoxygenated Type I water. 2-Ethylhexyl methacrylate and acomonomer of interest were separately stirred with inhibitor remover(available from Aldrich Chemical Co., designed to remove thepolymerization inhibitor 4-methoxy phenol) under a nitrogen atmospherefor at least one hour. After the desired time, the inhibitor remover wasseparated from the respective monomers by filtration under a nitrogenatmosphere. The desired amounts of the respective monomers were added tothe reaction kettle using syringe techniques. Stirring was initiated atabout 300 rpm and the kettle jacket was set to the desiredpolymerization temperature by using a circulating bath.

When ready to initiate polymerization, to the polymerization mixture inthe kettle was added 1.0 mL of FeSO₄ solution (0.0021 g/mL). Followingthis, 1.0 mL of ammonium persulfate solution (0.0026 g/mL) and 1.0 mL ofsodium formaldehyde sulfoxylate (SFS) solution (0.0018 g/mL) were eachadded over four hours. At the end of the four-hour period, to thepolymerization mixture 1.0 mL of tert-butyl hydroperoxide solution(0.0075 g/mL) and 1.0 mL SFS solution (0.0018 g/mL) were each added overtwo hours.

The resulting drag reducer was a latex containing a copolymer of2-ethylhexyl methacrylate and a comonomer. The samples had solidscontents of about 45 percent by mass and a nominal polymer content ofapproximately 40 percent. The densities of the samples wereapproximately 1.0005 g/mL. The carrier fluid for each sample was 100%water.

Dissolution Rate Testing

The dissolution rate constants of several copolymers prepared via theabove method were determined according to the following procedure. Therate at which a polymer dissolves can be determined by a vortexinhibition test in a kerosene-containing medium at various temperatures.At a constant stirring speed, the depth of the vortex is proportional tothe amount of dissolved polymer in the kerosene-containing medium. Thedissolution rate is a first order function:

d/dt(Conc_(undissolved))=−k×Conc_(undissolved)

wherein k is the dissolution rate constant. The time, T, for a certainfraction of the polymer to be dissolved is a function of k as follows:

T _(% dissolved)=[ln 100/(100−% dissolved)]/k

FIG. 1 schematically illustrates the dissolution rate test apparatusused to determine the dissolution rate constant. The dissolution ratetest apparatus included a rotating stirrer that was placed in a jacketedgraduated 250 mL cylinder having an internal diameter of 48 mm. Theupper end of the rotating stirrer was connected to a variable-speedmotor (not shown). The specific configuration of the rotating stirrer isillustrated in detail in FIGS. 2-4. The rotating stirrer employed in thedissolution rate tests was a Black & Decker paint stirrer made from acasting of oil resistant plastic. The stirrer head was formed of a 45 mmdiameter disk made up of a central disk and an outer ring. The centraldisk was 20 mm in diameter and 1.5 mm thick and was centered on a hubthat was 12 mm in diameter and 12 mm thick. The hub was drilled in thecenter for attachment of the stirring head to a 4 mm diameter shaft. Theshaft was threaded for 27 mm so that two small nuts held the stirringhead to the shaft. The outer ring was 45 mm in diameter, 9 mm wide, and1.5 mm thick. The outer ring was attached to the inner disk by 13 evenlyspaced arcs 13 mm long and 1 mm thick. The outer ring resided 6 mm belowthe level of the inner disk. The arcs that attached the outer ring tothe inner disk acted as paddles to stir the fluid in the test cylinder.The shaft that attached the stirring head to the stirring motor (notshown) was 300 mm long. It should be noted that dissolution rate testresults may vary somewhat if different stirrer configurations are used.

To conduct the dissolution rate test, the stirrer was positioned insidethe cylinder and adjusted so that the bottom of stirrer head was about 5millimeters from the bottom of the cylinder. The cylinder jacket wasthen filled with water recirculated from a recirculating water bath withcontrolled heating and cooling capability. The desired temperature wasselected and the bath was allowed to reach that temperature. With thestirrer in place, the jacketed graduated cylinder was filled to the 200mL line with a mixture comprising 95 volume percent kerosene and 5volume percent isopropyl alcohol (“IPA”). The circulation of coolingfluid through the graduated cylinder jacket was initiated. The kerosenemixture inside the graduated cylinder was stirred for sufficient time toallow the temperature to equilibrate at the set temperature, usually10-15 minutes. The kerosene mixture temperature was checked with athermometer to insure that the kerosene mixture was at the desired testtemperature. The speed of the motor was adjusted to stir rapidly enoughto form a vortex in the kerosene mixture that reached to the 125 mLgraduation mark in the cylinder.

A 0.5 mL aliquot of the polymer latex was added to the stirring kerosenemixture with the vortex established at the 125 mL mark. The aliquot ofthe latex was added to the kerosene at the desired temperature, asindicated in Tables 1 and 2 below. A timer was used to monitor andrecord the time required for the vortex to recede to each of the 5 mLincrements on the cylinder: 130, 135, 140, and so on. However, thedetermination was stopped when the time exceeded 30 minutes. Theposition of the vortex at the end of 30 minutes is designated as V_(f).

The dissolution rate constant, k, was calculated from the slope of aplot of the log of the relative vortex against time. The relative vortexis the decimal fraction of the relationship

[V _(f) −V _(t) ]/[V _(f) −V _(i)]

where V_(f) is the final reading at the maximum vortex suppressionwithin the 30 minute timeframe of the experiment, V_(i) is the initialvortex reading prior to addition of drag reducing polymer (which isroutinely set at the 125 mL mark), and V_(t) is the vortex reading atthe specified marks 130, 135, 140, and so on up to the reading at themaximum vortex suppression. A linear regression analysis was performedon the plot of the log of the relative vortex against time. Theresulting slope of the data gave the dissolution rate constant, k, for agiven temperature and concentration of active polymer when multiplied by−2.303.

Example 1 Comonomers with One or Less Pendant Substituents Per VinylCarbon

Copolymer latex drag reducers prepared from 2-ethylhexyl methacrylatemonomer and a variety of comonomers comprising a polymerizable vinylgroup having no more than one pendant substituent per vinyl carbon wereprepared according to the above-described procedure. Thereafter, thedissolution rate of each sample was tested and the dissolution rateconstant was calculated as described above. The results from theseprocedures are listed in Table 1.

TABLE 1 Dissolution Rates of Copolymers Comprising Comonomers Having Oneor Less Pendant Substituents per Vinyl Carbon Dissolution Rate ConstantMonomer Ratio In 95:5 Kerosene:IPA Copolymer (molar) 40° C. 30° C. 20°C. 2-ethylhexyl 100:0  N/A 0.361 0.273 methacrylate/ 84:16 N/A 0.7140.417 ethylhexyl acrylate 84:16 N/A 0.796 0.563 84:16 N/A 0.552 0.344100:0  N/A No Dissolution No Dissolution 95:5  N/A 0.118 0.017 89:11 N/A0.206 0.089 79:21 N/A 0.533 0.359 100:0  0.144 0.013 No Dissolution95:5  0.316 0.080 No Dissolution 90:10 0.266 0.197 0.074 84:16 0.4720.719 0.248 79:21 0.759 0.486 0.316 2-ethylhexyl 100:0  0.403 0.110 NoDissolution methacrylate/ 98.5:1.5  0.353 0.128 No Dissolution 3,5,5-95:5  0.355 0.230 0.065 trimethylhexyl 100:0  0.373 0.044 No Dissolutionacrylate 98.5:1.5  0.246 0.064 No Dissolution 95:5  0.500 0.102 NoDissolution 2-ethylhexyl 100:0  N/A No Dissolution No Dissolutionmethacrylate/ 94:6  N/A 0.093 No Dissolution n-hexyl acrylate 88:12 N/A0.368 0.135 77:23 N/A 0.508 0.472 100:0  N/A N/A No Dissolution 94:6 N/A N/A No Dissolution 88:12 N/A N/A 0.111 76:24 N/A N/A 0.540 100:0  NoDissolution No Dissolution No Dissolution 94:6  0.253 0.099 0.160 88:120.390 0.362 0.166 76:24 0.177 0.754 0.383 100:0  0.213 No Dissolution NoDissolution 99.4:0.6  0.277 0.070 No Dissolution 98:2  No Dissolution NoDissolution No Dissolution 94:6  0.396 0.176 0.120 94:6  0.507 0.1630.058 2-ethylhexyl 100:0  0.482 0.145 No Dissolution methacrylate/99.3:0.7  0.350 0.112 No Dissolution benzyl acrylate 97.8:2.2  0.5820.309 No Dissolution 2-ethylhexyl 100:0  N/A 0.073 No Dissolutionmethacrylate/ 93:7  N/A 0.141 No Dissolution t-butyl acrylate 86:14 N/A0.410 0.227 73:27 N/A 0.504 0.292 100:0  N/A No Dissolution NoDissolution 93:7  N/A 0.213 0.075 86:14 N/A 0.256 0.407 73:27 N/A 0.3670.174 100:0  N/A No Dissolution No Dissolution 93:7  N/A 0.250 0.09286:14 N/A 0.277 0.114 73:27 N/A 0.339 0.446 2-ethylhexyl 100:0  0.4110.120 No Dissolution methacrylate/ 99.4:0.6  0.327 0.126 No Dissolution2-phenylethyl 98:2  0.203 0.088 0.078 acrylate 94:6  0.269 0.143 0.06694:6  0.238 0.286 0.036 2-ethylhexyl 100:0  N/A 0.155 0.016methacrylate/ 93:7  N/A 0.158 0.089 n-butyl acrylate 86:14 N/A 0.6380.163 72:28 N/A 0.997 0.529 100:0  N/A N/A N/A 80:20 N/A 0.676 0.55460:40 N/A 0.506 0.513 40:60 N/A 0.534 0.508 100:0  N/A 0.175 0.137 80:20N/A 0.461 0.554 40:60 N/A 0.462 0.616 20:80 N/A 0.420 0.454 72:28 N/A0.586 0.270 72:28 N/A 0.601 0.274 72:28 N/A 0.625 0.464 73:27 N/A 0.5000.328 72:28 N/A 0.720 0.359 72:28 N/A 0.578 0.491 72:28 N/A 0.546 0.34073:27 N/A 0.439 0.331 100:0  N/A N/A No Dissolution 93:7  N/A N/A 0.01685:15 N/A N/A 0.182 73:27 N/A N/A 0.394 100:0  N/A N/A No Dissolution93:7  N/A N/A 0.019 85:15 N/A N/A 0.202 72:28 N/A N/A 0.539 100:0  N/AN/A No Dissolution 93:7  N/A N/A No Dissolution 86:14 N/A N/A 0.21072:28 N/A N/A 0.453 100:0  0.182 No Dissolution No Dissolution 98:2 0.585 0.220 No Dissolution 93:7  0.546 0.183 0.073 2-ethylhexyl 100:0 0.287 0.085 No Dissolution methacrylate/ 99.5:0.5  0.421 0.094 NoDissolution isodecyl acrylate 98.6:1.4  0.526 0.068 No Dissolution 96:4 0.259 0.121 No Dissolution 96:4  0.232 0.135 No Dissolution 2-ethylhexyl100:0  N/A 0.019 No Dissolution methacrylate/ 93:7  N/A 0.143 0.065isobutyl acrylate 85:15 N/A 0.190 0.106 72:28 N/A 0.414 0.335 100:0 0.077 No Dissolution No Dissolution 93:7  0.162 0.082 0.017 85:15 0.5670.408 0.251 72:28 1.000 0.838 0.614 2-ethylhexyl 100:0  0.070 NoDissolution No Dissolution methacrylate/ 99.5:0.5  0.082 No DissolutionNo Dissolution isobornyl acrylate 98.4:1.6  0.193 0.016 No Dissolution95:5  0.315 0.205 0.082 95:5  0.175 0.022 No Dissolution 2-ethylhexyl100:0  0.024 0.023 No Dissolution methacrylate/ 99.2:0.8  0.016 NoDissolution No Dissolution sec-butyl acrylate 98:2  0.028 No DissolutionNo Dissolution 93:7  0.256 0.099 0.094 93:7  0.224 0.106 No Dissolution2-ethylhexyl 100:0  0.032 No Dissolution No Dissolutionmethacrylate/ethyl 99:1  0.278 0.085 No Dissolution acrylate 98:2  0.072No Dissolution No Dissolution 90:10 0.436 0.331 0.086 90:10 0.379 0.1550.016 2-ethylhexyl 100:0  0.101 No Dissolution No Dissolutionmethacrylate/ 99:1  0.281 0.077 No Dissolution styrene 97:3  0.190 NoDissolution No Dissolution 2-ethylhexyl 100:0  0.194 0.013 NoDissolution methacrylate/ 99.7:0.3  0.081 No Dissolution No Dissolutionbis(2-ethylhexyl) 99:1  0.341 0.016 No Dissolution maleate 97:3  NoDissolution No Dissolution No Dissolution 97:3  No Dissolution NoDissolution No Dissolution 2-ethylhexyl 100:0  No Dissolution NoDissolution No Dissolution methacrylate/ 99.7:0.3  0.227 0.010 NoDissolution bis(2-ethylhexyl) 99:1  0.155 0.013 No Dissolution fumarate97:3  0.189 No Dissolution No Dissolution 97:3  0.075 No Dissolution NoDissolution

In addition to the above, one sample drag reducer comprising an 80:20molar ratio blend of 2-ethylhexyl methacrylate to n-butyl acrylate wastested at 10° C. This sample yielded a dissolution rate constant of0.191.

Example 2 Comonomers with More than One Pendant Substituent on a VinylCarbon

Copolymer latex drag reducers prepared from 2-ethylhexyl methacrylatemonomer and a variety of comonomers comprising a polymerizable vinylgroup with at least one vinyl carbon having more than one pendantsubstituent were prepared according to the above-described procedure.Thereafter, the dissolution rate of each sample was tested and thedissolution rate constant was calculated as described above. The resultsfrom these procedures are listed in Table 2.

TABLE 2 Dissolution Rates of Copolymers Comprising Comonomers HavingMore Than One Pendant Substituent on a Vinyl Carbon Dissolution RateConstant Monomer Ratio In 95:5 Kerosene:IPA Copolymer (molar) 40° C. 30°C. 20° C. 2-ethylhexyl 100:0  No Dissolution No Dissolution NoDissolution methacrylate/ 96:4  No Dissolution No Dissolution NoDissolution lauryl methacrylate 2-ethylhexyl 100:0  0.051 No DissolutionNo Dissolution methacrylate/ 98.5:1.5  0.245 No Dissolution NoDissolution n-octyl methacrylate 2-ethylhexyl 100:0  No Dissolution NoDissolution No Dissolution methacrylate/ 94:6  No Dissolution NoDissolution No Dissolution benzyl methacrylate 2-ethylhexyl 100:0  0.028No Dissolution No Dissolution methacrylate/ 93:7  No Dissolution NoDissolution No Dissolution t-butyl methacrylate 2-ethylhexyl 100:0 0.216 No Dissolution No Dissolution methacrylate/ 96:4  0.035 0.017 NoDissolution 2-phenylethyl methacrylate 2-ethylhexyl 100:0  N/A 0.2140.155 methacrylate/ 80:20 N/A 0.053 No Dissolution n-butyl 40:60 N/A NoDissolution No Dissolution methacrylate 100:0  0.110 No Dissolution NoDissolution 98:2  0.117 No Dissolution No Dissolution 93:7  0.251 NoDissolution No Dissolution 2-ethylhexyl 100:0  0.329 0.055 0.014methacrylate/ 98:2  0.089 0.013 No Dissolution cyclohexyl 94:6  0.1460.011 No Dissolution methacrylate 2-ethylhexyl 100:0  No Dissolution NoDissolution No Dissolution methacrylate/ 98.7:1.3  No Dissolution NoDissolution No Dissolution isodecyl methacrylate 2-ethylhexyl 100:0  NoDissolution No Dissolution No Dissolution methacrylate/ 93.5:6.5  NoDissolution No Dissolution No Dissolution isobutyl methacrylate2-ethylhexyl 100:0  0.186 0.020 No Dissolution methacrylate/ 99.7:0.3 0.389 0.098 No Dissolution hexadecyl 97:3  0.025 No Dissolution NoDissolution methacrylate 2-ethylhexyl 100:0  0.140 No Dissolution NoDissolution methacrylate/ 99.5:0.5  0.393 0.072 No Dissolution isobornyl95:5  0.334 0.112 No Dissolution methacrylate 2-ethylhexyl 100:0  0.4170.118 No Dissolution methacrylate/ 99.6:0.4  0.047 No Dissolution NoDissolution tridecyl 99:1  No Dissolution No Dissolution No Dissolutionmethacrylate 96:4  No Dissolution No Dissolution No Dissolution 96:4  NoDissolution No Dissolution No Dissolution 2-ethylhexyl 100:0  0.022 NoDissolution No Dissolution methacrylate/ 99.5:0.5  0.026 No DissolutionNo Dissolution dibutyl itaconate 98.7:1.3  0.456 0.085 No Dissolution96:4  0.101 0.012 No Dissolution 95:5  0.354 0.120 0.085

As can be seen by comparing Tables 1 and 2, preparing a copolymer from a2-ethylhexyl methacrylate monomer and a comonomer comprising apolymerizable vinyl group having no more than one pendant substituentper vinyl carbon produces a drag reducer having better dissolution rateconstants at lower temperatures than when a comonomer having more thanone substituent on a vinyl carbon is employed. For example, only one ofthe copolymers containing a comonomer having more than one substituenton a vinyl carbon (i.e., dibutyl itaconate) prepared in Example 2 wasable to be dissolved according to the above-described procedure at atemperature of 20° C.¹ By comparison, of the 15 copolymer samples testedcontaining a comonomer having no more than one pendant substituent pervinyl carbon, 10 were able to be dissolved at 20° C. in at least one ofthe sample ratios prepared. Additionally, at least one sample preparedemploying a comonomer having no more than one pendant substituent pervinyl carbon (i.e., n-butyl acrylate) was able to be dissolved at 10° C.Accordingly, comonomers comprising a polymerizable vinyl group having nomore than one pendant substituent per vinyl carbon appear to producedrag reducing copolymers having improved dissolution rate constants atlower temperatures over comonomers having more than one pendantsubstituent on a vinyl carbon. This is even more evident by comparingpolymers that differ only with respect to the presence or absence of thesecond pendant group. As an example, the dissolution rate constant, k,for 80:20 EHMA/n-butyl acrylate is about 0.5 min⁻¹ at 20° C. anddissolves much more rapidly compared to the control EHMA homopolymerwhile the corresponding EHMA/n-butyl methacrylate polymer does not evendissolve at 20° C. under the test conditions. ¹Note that the entries forn-butyl methacrylate and cyclohexyl methacrylate comonomers do indicatesome dissolution at 20° C.; however, no comonomer was present in thesamples exhibiting dissolution (i.e., the monomer-to-comonomer ratio was100:0).

Numerical Ranges

The present description uses numerical ranges to quantify certainparameters relating to the invention. It should be understood that whennumerical ranges are provided, such ranges are to be construed asproviding literal support for claim limitations that only recite thelower value of the range as well as claims limitation that only recitethe upper value of the range. For example, a disclosed numerical rangeof 10 to 100 provides literal support for a claim reciting “greater than10” (with no upper bounds) and a claim reciting “less than 100” (with nolower bounds).

DEFINITIONS

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or more elements recited after the term, wherethe element or elements listed after the transition term are notnecessarily the only elements that make up the subject.

As used herein, the terms “including,” “includes,” and “include” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise.”

As used herein, the terms “containing,” “contains,” and “contain” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “a,” “an,” “the,” and “said” mean one or more.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itselfor any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

Claims not Limited to the Disclosed Embodiments

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Obvious modifications tothe exemplary embodiments, set forth above, could be readily made bythose skilled in the art without departing from the spirit of thepresent invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention as set forth in thefollowing claims.

What is claimed is:
 1. A drag reducing composition comprising: acontinuous phase and a plurality of drag reducing polymer particles,wherein at least a portion of said polymer particles comprise copolymerscontaining the residues of at least one methacrylate monomer and theresidues of at least one comonomer, wherein said comonomer comprises apolymerizable vinyl group having no more than one pendant substituentper vinyl carbon.
 2. The composition of claim 1, wherein said copolymerscomprise saturated hydrocarbon backbones comprising a plurality ofcarbon atoms, wherein fewer than 50 percent of said carbon atoms havemore than one pendant substituent.
 3. The composition of claim 1,wherein said copolymers comprise saturated hydrocarbon backbonescomprising a plurality of carbon atoms, wherein fewer than 45 percent ofsaid carbon atoms have more than one pendant substituent.
 4. Thecomposition of claim 1, wherein said methacrylate monomer has thefollowing structure:

wherein R₁ is a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl.
 5. The composition of claim 1, wherein saidmethacrylate monomer comprises C₄-C₂₀ alkyl, C₆-C₂₀ substituted orunsubstituted aryl, or aryl-substituted C₁-C₁₀ alkyl esters ofmethacrylic acid.
 6. The composition of claim 1, wherein saidmethacrylate monomer comprises 2-ethylhexyl methacrylate.
 7. Thecomposition of claim 1, wherein said comonomer comprises one or more ofthe following structures:

wherein R₂ is —C(O)OR₃, phenyl or aryl, heterocyclic, —OR₄, or —O(O)CR₅;wherein R₃ is a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl; wherein R₄ is a C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, or aryl-substituted alkyl; wherein R₅ is a C₁ to C₂₀alkyl, isoalkyl, cycloalkyl, aryl, or aryl-substituted alkyl; and/or

wherein X is O, or N—R₆, wherein R₆ is H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or ring-opened alkyl diesters;and/or

wherein R7 and R8 can independently be H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or heterocyclic.
 8. Thecomposition of claim 1, wherein said comonomer is an acrylate having thefollowing structure:

wherein R₉ is a straight or branched aliphatic alkyl group having 8 orfewer carbon atoms.
 9. The composition of claim 8, wherein R₉ is astraight or branched aliphatic alkyl group having 6 or fewer carbonatoms.
 10. The composition of claim 1, wherein said comonomer isselected from the group consisting of n-butyl acrylate; 2-ethylhexylacrylate; 3,5,5-trimethylhexyl acrylate; tert-butyl acrylate;2-phenylethyl acrylate; iso-butyl acrylate; isobornyl acrylate; n-hexylacrylate; sec-butyl acrylate; ethyl acrylate; and lauryl acrylate. 11.The composition of claim 1, wherein said comonomer comprises n-butylacrylate.
 12. The composition of claim 1, wherein said copolymerscomprise residues of said comonomer in an amount in the range of fromabout 1 to about 90 weight percent based on the total weight of thecopolymer.
 13. The composition of claim 1, wherein said copolymerscomprise residues of said comonomer in an amount in the range of fromabout 3 to about 80 weight percent based on the total weight of thecopolymer.
 14. The composition of claim 1, wherein said copolymerscomprise residues of said methacrylate monomer in an amount in the rangeof from about 10 to about 99 weight percent based on the total weight ofthe copolymer.
 15. The composition of claim 1, wherein said polymerparticles have a hydrocarbon dissolution rate constant of at least about0.01 min⁻¹ at 20° C. in a mixture of kerosene and isopropyl alcohol(“IPA”) in a volume ratio of 95:5 kerosene:IPA.
 16. The composition ofclaim 1, wherein said continuous phase comprises water, one or morealcohols, and/or one or more polyols.
 17. The composition of claim 1,wherein said drag reducing composition comprises said polymer particlesin an amount in the range of from about 10 to about 60 weight percentbased on the total weight of said drag reducing composition.
 18. Thecomposition of claim 1, wherein said polymer particles have a weightaverage molecular weight of at least 1×10⁶ g/mol.
 19. The composition ofclaim 1, wherein said drag reducing composition comprises an emulsiondrag reducing polymer wherein said polymer particles have an averageparticle size in the range of from about 10 to about 500 nm.
 20. Thecomposition of claim 1, wherein said drag reducing composition comprisesa suspension drag reducing polymer wherein said polymer particles havean average particle size in the range of from about 1 to about 500micrometers.
 21. A method of making a drag reducer, said methodcomprising: (a) combining water, at least one surfactant, at least onemethacrylate monomer, and at least one comonomer to thereby form areaction mixture; and (b) subjecting said reaction mixture topolymerization to thereby form a composition comprising a continuousphase and a plurality of drag reducing copolymer particles comprisingresidues of said methacrylate monomer and residues of said comonomer,wherein said comonomer comprises a polymerizable vinyl group having nomore than one pendant substituent per vinyl carbon.
 22. The method ofclaim 21, wherein said copolymers comprise saturated hydrocarbonbackbones comprising a plurality of carbon atoms, wherein fewer than 50percent of said carbon atoms have more than one pendant substituent. 23.The method of claim 21, wherein said copolymers comprise saturatedhydrocarbon backbones comprising a plurality of carbon atoms, whereinfewer than 45 percent of said carbon atoms have more than one pendantsubstituent.
 24. The method of claim 21, wherein said methacrylatemonomer has the following structure:

wherein R₁ is a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl.
 25. The method of claim 21, wherein saidmethacrylate monomer comprises 2-ethylhexyl methacrylate.
 26. The methodof claim 21, wherein said comonomer comprises one or more of thefollowing structures:

wherein R₂ is —C(O)OR₃, phenyl or aryl, heterocyclic, —OR₄, or —O(O)CR₅;wherein R₃ is a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl; wherein R₄ is a C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, or aryl-substituted alkyl; wherein R₅ is a C₁ to C₂₀alkyl, isoalkyl, cycloalkyl, aryl, or aryl-substituted alkyl; and/or

wherein X is O or N—R₆, wherein R₆ is H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or ring-opened alkyl diesters;and/or

wherein R7 and R8 can independently be H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or heterocyclic.
 27. Themethod of claim 21, wherein said comonomer is an acrylate having thefollowing structure:

wherein R₉ is a straight or branched aliphatic alkyl group having 8 orfewer carbon atoms.
 28. The method of claim 21, wherein said comonomercomprises n-butyl acrylate.
 29. The method of claim 21, wherein saidcopolymers comprise residues of said comonomer in an amount in the rangeof from about 1 to about 90 weight percent based on the total weight ofthe copolymer.
 30. The method of claim 21, wherein said copolymerscomprise residues of said methacrylate monomer in an amount in the rangeof from about 10 to about 99 weight percent based on the total weight ofthe copolymer.
 31. The method of claim 20, wherein said polymerparticles have a hydrocarbon dissolution rate constant of at least about0.01 min⁻¹ at 20° C. in a mixture of kerosene and isopropyl alcohol(“IPA”) in a volume ratio of 95:5 kerosene:IPA.
 32. The method of claim21, wherein said drag reducing composition comprises said copolymerparticles in an amount in the range of from about 10 to about 60 weightpercent based on the total weight of said drag reducing composition. 33.The method of claim 21, wherein said copolymer particles have a weightaverage molecular weight of at least 1×10⁶ g/mol.
 34. The method ofclaim 21, wherein said drag reducing copolymer comprises an emulsiondrag reducing polymer wherein said copolymer particles have an averageparticle size in the range of from about 10 to about 500 nm.
 35. Themethod of claim 21, wherein said drag reducing copolymer comprises asuspension drag reducing polymer wherein said polymer particles have anaverage particle size in the range of from about 1 to about 500micrometers.
 36. A method for reducing the pressure drop associated withthe turbulent flow of a hydrocarbon-containing fluid through a pipeline,said method comprising: (a) introducing a drag reducing composition intosaid hydrocarbon-containing fluid, wherein said drag reducingcomposition comprises a continuous phase and a plurality of dragreducing polymer particles comprising copolymers containing the residuesof at least one methacrylate monomer and the residues of at least onecomonomer, wherein said comonomer comprises a polymerizable vinyl grouphaving no more than one pendant substituent per vinyl carbon; and (b)flowing the resulting treated hydrocarbon-containing fluid through saidpipeline, wherein said hydrocarbon-containing fluid has an averagetemperature of 25° C. or less.
 37. The method of claim 36, wherein saidcopolymers comprise saturated hydrocarbon backbones comprising aplurality of carbon atoms, wherein fewer than 50 percent of said carbonatoms have more than one pendant substituent.
 38. The method of claim36, wherein said copolymers comprise saturated hydrocarbon backbonescomprising a plurality of carbon atoms, wherein fewer than 45 percent ofsaid carbon atoms have more than one pendant substituent.
 39. The methodof claim 36, wherein said methacrylate monomer has the followingstructure:

wherein R₁ is a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl.
 40. The method of claim 36, wherein saidmethacrylate monomer comprises C₄-C₂₀ alkyl, C₆-C₂₀ substituted orunsubstituted aryl, or aryl-substituted C₁-C₁₀ alkyl esters ofmethacrylic acid.
 41. The method of claim 36, wherein said methacrylatemonomer comprises 2-ethylhexyl methacrylate.
 42. The method of claim 36,wherein said comonomer comprises one or more of the followingstructures:

wherein R₂ is —C(O)OR₃, phenyl or aryl, heterocyclic, —OR₄, or —O(O)CR₅;wherein R₃ is a C₁ to C₂₀ alkyl, isoalkyl, cycloalkyl, aryl, oraryl-substituted alkyl; wherein R₄ is a C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, or aryl-substituted alkyl; wherein R₅ is a C₁ to C₂₀alkyl, isoalkyl, cycloalkyl, aryl, or aryl-substituted alkyl; and/or

wherein X is O, or N—R₆, wherein R₆ is H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or ring-opened alkyl diesters;and/or

where R₇ and R₈ can independently be H, C₁ to C₂₀ alkyl, isoalkyl,cycloalkyl, aryl, aryl-substituted alkyl, or heterocyclic.
 43. Themethod of claim 36, wherein said comonomer is an acrylate having thefollowing structure:

wherein R₉ is a straight or branched aliphatic alkyl group having 8 orfewer carbon atoms.
 44. The method of claim 36, wherein said comonomeris selected from the group consisting of n-butyl acrylate; 2-ethylhexylacrylate; 3,5,5-trimethylhexyl acrylate; tert-butyl acrylate;2-phenylethyl acrylate; iso-butyl acrylate; isobornyl acrylate; n-hexylacrylate; sec-butyl acrylate; ethyl acrylate; and lauryl acrylate. 45.The method of claim 36, wherein said comonomer comprises n-butylacrylate.
 46. The method of claim 36, wherein said copolymers compriseresidues of said comonomer in an amount in the range of from about 1 toabout 90 weight percent based on the total weight of the copolymer. 47.The method of claim 36, wherein said copolymers comprise residues ofsaid methacrylate monomer in an amount in the range of from about 10 toabout 99 weight percent based on the total weight of the copolymer. 48.The method of claim 36, wherein said polymer particles have ahydrocarbon dissolution rate constant of at least about 0.01 min⁻¹ at20° C. in a mixture of kerosene and isopropyl alcohol (“IPA”) in avolume ratio of 95:5 kerosene:IPA.
 49. The method of claim 36, whereinsaid hydrocarbon-containing fluid has an average temperature of 22° C.or less.
 50. The method of claim 36, wherein said treatedhydrocarbon-containing fluid has a cumulative concentration of saidcopolymers in the range of from about 0.1 to about 500 ppmw.
 51. Themethod of claim 36, wherein said hydrocarbon-containing fluid comprisesa liquid phase hydrocarbon, a non-liquid phase hydrocarbon, and/or anon-hydrocarbon fluid, wherein said hydrocarbon-containing fluidcomprises said liquid phase hydrocarbon in an amount of at least about50 weight percent based on the total weight of thehydrocarbon-containing fluid.
 52. The method of claim 36, wherein saidhydrocarbon-containing fluid comprises crude oil.